Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University CREST, Japan Science and Technology Agency

Yuki Totani

Department of Biology, Waseda University

Manabu Sakakibara

Research Organization for Nano and Life Innovation, Waseda University

Ken Lukowiak

Hotchkiss Brain Institute, University of Calgary

Etsuro Ito

Department of Biology, Waseda University Research Organization for Nano and Life Innovation, Waseda University WASEDA Bioscience Research Institute in Singapore Graduate Institute of Medicine and Center for Stem Cell Research, Kaohsiung Medical University

To find a causal mechanism of learning and memory is a heuristically important topic in neuroscience. In the pond snail Lymnaea stagnalis, the following experimental facts have accrued regarding a classical conditioning procedure known as conditioned taste aversion (CTA): (1) one-day food-deprived Dutch snails have superior CTA memory formation; (2) the one-day food-deprived snails have a low monoamine content (e.g., serotonin, dopamine, octopamine) in their central nervous system (CNS); (3) fed or five-day food-deprived snails have poorer CTA memory and a higher monoamine content; (4) the Dutch snails form better CTA memory than the Canadian TC1 strain; and, (5) the F1 cross snails between the Dutch and Canadian TC1 strains also form poor CTA memory. Here, in one-day food-deprived snails, we measured the monoamine content in the CNSs of the 3 populations. In most instances, the monoamine content of the Dutch strain was lower than in the other two populations. The F1 cross snails had the highest monoamine content. A lower monoamine content is correlated with the better CTA memory formation.